CN110590604A - Continuous rectification and purification device for m-phthalonitrile - Google Patents
Continuous rectification and purification device for m-phthalonitrile Download PDFInfo
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- CN110590604A CN110590604A CN201910990199.XA CN201910990199A CN110590604A CN 110590604 A CN110590604 A CN 110590604A CN 201910990199 A CN201910990199 A CN 201910990199A CN 110590604 A CN110590604 A CN 110590604A
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
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- C07C253/34—Separation; Purification
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Abstract
The invention provides an m-phthalonitrile continuous rectification purification device, which comprises a scraper evaporator and a rectifying tower which are sequentially connected, can continuously and stably produce and has low operation cost; the device can realize the continuous and stable purification of the isophthalonitrile, obtain the product with the purity of the isophthalonitrile being more than or equal to 99.83 wt%, and reduce the content of cyanobenzamide in the product, thereby reducing the quality of residue in a melter in a chlorothalonil production device, reducing the content of hexachlorobenzene in downstream chlorothalonil products, and relieving the environmental pressure.
Description
Technical Field
The invention relates to the field of pesticide refining, in particular to an m-phthalonitrile continuous rectification and purification device.
Background
Isophthalonitrile (IPN) is an important organic raw material for organic synthesis, and is used for preparing plastics, synthetic fibers, pesticides (chlorothalonil), epoxy resin curing agents and the like. Tetrachloroisophthalonitrile synthesized by chlorination of isophthalonitrile is a high-efficiency and low-toxicity bactericide; the m-xylylenediamine prepared by hydrogenation of m-phthalonitrile is an epoxy resin curing agent with excellent performance, and is also a raw material of polyurethane and nylon resin.
At present, the main method for synthesizing isophthalonitrile is an ammoxidation method, namely, m-xylene, ammonia gas and oxygen are subjected to ammoxidation reaction under the action of a catalyst to prepare isophthalonitrile. However, the isophthalonitrile produced by the ammoxidation method has low purity and high amide content, and is crude isophthalonitrile. The crude isophthalonitrile can provide raw materials for subsequent organic synthesis after purification and refining, the main trapping modes of the isophthalonitrile at present are thin-wall trapping and water spraying trapping, but the isophthalonitrile products obtained by the two trapping methods still have high amide content, the high amide content can cause more residues in a melter in the production process of downstream chlorothalonil, and the impurity hexachlorobenzene in the chlorothalonil products can also have high content and great harm to the environment.
CN201384868Y discloses a water spraying and trapping method for trapping and recovering isophthalonitrile in a water mist mode by adopting a spray tower, a secondary absorption tower, a filter press and a drying tower device, which reduces the device investment cost to a certain extent. However, the method adopts a filter press to separate the solid-liquid mixture, the filter press is intermittent equipment and cannot be continuously operated with subsequent drying equipment, and ammonia gas escapes from the filter press in the operation process to greatly influence the labor environment of workers.
CN106892839B discloses a method for refining isophthalonitrile, which comprises the steps of introducing a crude isophthalonitrile raw material into a distillation kettle, cooling steam of the distilled isophthalonitrile through a heat exchanger, introducing into a receiving kettle for heat preservation, and finally slicing through a slicing machine to obtain a refined isophthalonitrile finished product; the method improves the purity of the intermediate phthalonitrile product, but the method adopts the intermittent distillation process to refine the isophthalonitrile, the refined isophthalonitrile product content is only 99.5 percent, and the intermittent process not only easily causes the instability of the product quality, but also is difficult to realize continuous production, and increases the production cost.
CN1202072C discloses a method for refining and purifying isophthalonitrile by adopting a two-stage rectifying tower, which improves the quality and the recovery rate of products; however, the method adopts two-stage rectifying towers, so that the energy consumption is high, the isophthalonitrile has thermal instability, and the modification or deterioration can occur in the primary de-heavy rectification process due to the long rectification time, so that the reactions such as amidation, polymerization and the like are caused, and the yield and the quality of the product are reduced.
In conclusion, the prior art has the problems of high amide content in the isophthalonitrile product, unstable product quality, low yield, difficulty in continuous production and the like, and the high amide content causes more residues in a melter in the production process of downstream chlorothalonil, and causes high content of impurity hexachlorobenzene in the chlorothalonil product and great harm to the environment.
Therefore, it is required to develop a continuous and stable production device of isophthalonitrile with high yield, high purity and low content of m-cyanobenzamide, so as to reduce the content of hexachlorobenzene in the subsequent chlorothalonil product, reduce the residue in a melter in the chlorothalonil production device and reduce the production cost.
Disclosure of Invention
In view of the problems in the prior art, the invention provides an isophthalonitrile continuous rectification and purification device, which combines a scraper evaporator and a rectification tower, so that an isophthalonitrile raw material is vaporized in the scraper evaporator and then enters the middle section of the rectification tower for rectification and purification, the problems of unstable quality and low purity of an isophthalonitrile product are solved, continuous and stable production can be realized, the production cost and the amide content in the product are reduced, the content of hexachlorobenzene in a downstream chlorothalonil product is obviously reduced, the product quality of the chlorothalonil is improved, and the environmental pressure is relieved.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides an m-phthalonitrile continuous rectification purification device which comprises a raw material supply unit and a purification unit which are sequentially connected, wherein the raw material supply unit comprises a scraper evaporator, the purification unit comprises a rectification tower, and the top of the scraper evaporator is connected with the middle section of the rectification tower through a pipeline.
The device provided by the invention comprises the scraper evaporator and the rectifying tower which are sequentially connected, the device can stably and continuously operate and is low in operation cost, wherein the scraper evaporator can ensure that isophthalonitrile continuously and stably enters the middle section of the rectifying tower in a gas phase form, and the rectifying tower can realize high-efficiency separation and recovery of the isophthalonitrile, so that an isophthalonitrile product with high yield and high purity is obtained, the content of cyanobenzamide in the middle of the product is remarkably reduced, the content of hexachlorobenzene in a downstream chlorothalonil product is reduced, the product quality of the chlorothalonil is improved, and the environmental pressure is relieved.
Preferably, the stirring device is provided inside the scraper evaporator in the raw material supply unit.
Preferably, the scraper of the scraper evaporator is in the form of a limiting hinge scraper, a flexible scraper, a hinge scraper, an elastic scraper, a scraper-type scraper, a movable scraper or a fixed scraper.
Preferably, the wiped film evaporator is jacketed.
Preferably, heat conducting oil is adopted to heat the inside of a jacket of the scraper evaporator.
Preferably, the material of the scraper evaporator is stainless steel, Monel 400 or Hastelloy, and is preferably stainless steel 304.
Preferably, the raw material supply unit further comprises a feed metering pump and a melting intermediate tank which are connected in sequence by a pipe.
According to the invention, the feeding metering pump and the melting intermediate tank are arranged in front of the scraper evaporator, so that the isophthalonitrile raw material is melted in the melting intermediate tank, a certain buffering effect is achieved, the raw material entering the scraper evaporator is ensured to be a liquid phase with stable flow, and the continuous operation stability of the device is further improved.
Preferably, the feed metering pump is a plunger metering pump.
Preferably, the melting intermediate tank and the scraper evaporator are connected in sequence.
Preferably, the outlet of the melting intermediate tank is provided with a mass flow meter.
According to the invention, the mass flow meter is arranged at the outlet of the melting intermediate tank, so that the outlet flow of the melting intermediate tank can be regulated and controlled, and the stable flow of the liquid entering the scraper evaporator from the melting intermediate tank is ensured, thereby further improving the running stability of the device and further ensuring the purity and yield of the isophthalonitrile product.
Preferably, the melting intermediate tank is jacketed.
Preferably, heat conducting oil is adopted to heat the jacket of the melting intermediate tank.
Preferably, the material of the melting intermediate tank is stainless steel, Monel 400 or Hastelloy, and the material is preferably stainless steel 304.
Preferably, the raw material supply unit further comprises a coke cutting kettle connected with the scraper evaporator.
According to the invention, the coke cutting kettle connected with the scraper evaporator is a reaction kettle with a stirrer, so that unvaporized raw materials in the scraper evaporator can be collected and recycled in time, the bottom of the scraper evaporator is prevented from being coked, and the continuous stability of the scraper evaporator can be further improved.
Preferably, the top of the coke cutting kettle is connected with the bottom of the scraper evaporator.
Preferably, a first valve is arranged on a pipeline connecting the top of the coke cutting kettle with the bottom of the scraper evaporator.
Preferably, the top of the coke cutting kettle is connected with a top outlet pipeline of the scraper evaporator.
Preferably, a second valve is arranged on a pipeline connecting the top of the coke cutting kettle with a top outlet pipeline of the scraper evaporator.
Preferably, the top of the coke cutting kettle is respectively connected with the bottom of the scraper evaporator and a top outlet pipeline.
The device provided by the invention connects the top of the coke cutting kettle with the bottom of the scraper evaporator and the top outlet pipeline, wherein the pipeline connected with the top outlet pipeline can communicate the pressure of the coke cutting kettle with the pressure of the scraper evaporator, and when the pressure of the coke cutting kettle is the same as the pressure of the scraper evaporator, the bottom of the scraper evaporator is communicated with the pipeline at the top of the coke cutting kettle, so that the incompletely vaporized isophthalonitrile raw material flows into the coke cutting kettle, the intermittent operation of the coke cutting kettle can be realized, the liquid in the coke cutting kettle is prevented from being sucked into the scraper evaporator, and the quality of isophthalonitrile products and the stability of the operation of the scraper evaporator are prevented from being influenced.
Preferably, a discharge hole is formed in the top of the coke cutting kettle.
Preferably, a discharge hole in the top of the coke cutting kettle is provided with a third valve.
Preferably, the coke cutting kettles are arranged in at least two numbers.
According to the invention, by arranging at least two coke cutting kettles, the unvaporized raw materials can be thrown into the upstream intermittent process distillation kettle for recycling through the coke cutting kettles operated intermittently in turn while the coking at the bottom of the scraper evaporator is prevented, and the utilization rate of resources is improved.
Preferably, the number of the coke cutting kettles is two, namely a first coke cutting kettle and a second coke cutting kettle.
Preferably, the coke cutting kettle is provided with a jacket.
Preferably, heat conducting oil is adopted to heat the jacket of the coke cutting kettle.
Preferably, the material of the coke cutting kettle is stainless steel, Monel 400 or Hastelloy, and stainless steel 304 is preferred.
Preferably, the top of the rectifying tower of the purification unit is provided with an overhead condenser.
Preferably, the overhead condenser is a shell and tube condenser.
Preferably, the overhead condenser is provided with a side draw outlet.
Preferably, the bottom of the rectifying tower is provided with a tower bottom reboiler.
Preferably, the bottom reboiler is a shell and tube reboiler.
Preferably, the rectifying tower is internally provided with packing or trays.
Preferably, the outer wall of the rectifying tower is provided with a heat tracing pipe.
Preferably, the material of the body of the rectifying tower is stainless steel, Monel 400 or Hastelloy, and stainless steel 304 is preferred.
Preferably, the top outlet of the rectifying tower of the purification unit is provided with a secondary condenser.
In the device, the secondary condenser is arranged at the outlet of the top of the rectifying tower, so that the isophthalonitrile in the top of the non-condensable gas is condensed into a liquid-phase product, and the yield of the isophthalonitrile is further improved.
Preferably, the secondary condenser is a shell and tube heat exchanger.
Preferably, a slag discharging groove is arranged at the bottom outlet of the rectifying tower.
According to the device provided by the invention, the slag discharging groove is arranged at the bottom of the rectifying tower, so that high-boiling-point substances at the bottom of the rectifying tower can be discharged in time, the heat loss at the bottom of the rectifying tower is reduced, the coking phenomenon is relieved, and the stability of the operation of the device is further ensured.
Preferably, the slag discharging groove is provided with a jacket.
Preferably, heat conducting oil is adopted to heat in a jacket of the slag discharging groove.
Preferably, the material of the secondary condenser is stainless steel, Monel 400 or Hastelloy, and stainless steel 304 is preferred.
Preferably, the material of the slag discharge groove is stainless steel, Monel 400 or Hastelloy, and stainless steel 304 is preferred.
Preferably, the apparatus further comprises a product receiving unit after the purification unit.
Preferably, the product receiving unit comprises a product receiving vessel connected to the rectification column.
Preferably, the top of the product receiving vessel is connected to the side draw of the overhead condenser.
Preferably, the top of the product receiving vessel is connected to the bottom of the secondary condenser.
Preferably, the product receiving vessel is jacketed.
Preferably, the jacket of the product receiving kettle is heated by heat conducting oil.
Preferably, the material of the product receiving kettle is stainless steel, Monel 400 or Hastelloy, and stainless steel 304 is preferred.
Preferably, the bottom of the product receiving kettle in the product receiving unit is provided with a slicing machine or a material beating metering pump.
Preferably, the ramming material metering pump is a plunger type metering pump.
Preferably, the top outlet of the product receiving vessel is provided with a product condenser.
Preferably, the top of the product condenser, and/or the bottom of the product condenser is connected to the top of the product receiving vessel.
According to the invention, the top and the bottom of the product condenser are connected with the top of the product receiving kettle at the same time, so that on one hand, gas-phase isophthalonitrile which is not completely condensed in the product receiving kettle enters the product condenser through the top of the product condenser for condensation and collection, and on the other hand, the condensed and collected isophthalonitrile is returned to the product receiving kettle from the bottom of the product condenser to be an isophthalonitrile product, thereby improving the yield of isophthalonitrile.
Preferably, the material of the product condenser is stainless steel, Monel 400 or Hastelloy, and preferably stainless steel 304.
Preferably, the product receiving unit is provided with a product catcher at the top of the product receiving vessel.
Preferably, the interior of the product trap is provided with a baffle.
Preferably, a filter screen is arranged at the gas phase outlet of the product trap.
Preferably, the product traps are provided in at least two.
Preferably, the product traps are provided in two, respectively a first product trap and a second product trap.
Preferably, the product trap is provided with a jacket around it.
Preferably, the jacket of the product catcher is internally filled with circulating cooling water, cold air, low-temperature water or frozen brine.
Preferably, the material of the product catcher is carbon steel or stainless steel.
Preferably, the product trap is connected to a vacuum pump.
Preferably, the vacuum pump is a water-ring vacuum pump, a piston vacuum pump or a roots vacuum pump, preferably a water-ring vacuum pump.
Preferably, the material of the vacuum pump is carbon steel or stainless steel.
Preferably, connecting pipelines among the feeding metering pump, the melting intermediate tank, the scraper evaporator, the coke cutting kettle, the rectifying tower, the secondary condenser and the product receiving kettle are all jacketed pipelines.
Preferably, the material of the jacket pipeline is stainless steel, Monel 400 or Hastelloy, and the jacket pipeline is preferably stainless steel 304.
The device provided by the invention can be carried out by adopting the following processes:
(1) introducing an m-phthalonitrile raw material into a melting intermediate tank with the temperature of 150-260 ℃ for melting;
(2) vaporizing the isophthalonitrile raw material flowing out of the melting intermediate tank in a scraper evaporator with the temperature of 220-310 ℃ and the vacuum degree of 0.07-0.098 MPa, intermittently flowing liquid-phase isophthalonitrile incompletely vaporized in the scraper evaporator into at least two coke cutting kettles with the temperature of 150-260 ℃, and collecting for later use;
(3) introducing the vaporized isophthalonitrile in the scraper evaporator into the middle section of a rectifying tower, rectifying and purifying to obtain purified isophthalonitrile, extracting liquid-phase phthalonitrile from a side line extraction outlet of a condenser at the top of the rectifying tower, introducing non-condensable gas at the top of the rectifying tower into a secondary condenser for secondary condensation, putting high-boiling-point substances at the bottom of the rectifying tower into a slag discharge tank, periodically discharging slag and barreling, wherein the vacuum degree of the rectifying tower is 0.07-0.098 MPa, the temperature of the rectifying section is 150-210 ℃, the temperature of the stripping section is 220-310 ℃, the temperature of the condenser at the top of the rectifying tower is 150-210 ℃, the temperature of a reboiler at the bottom of the tower is 220-310 ℃, the temperature of the secondary condenser is 150-210 ℃ and the temperature of the slag discharge tank is 220-310 ℃;
(4) and introducing the liquid-phase phthalonitrile extracted from the side draw outlet of the overhead condenser and the liquid-phase phthalonitrile extracted from the bottom of the secondary condenser into a product receiving kettle with the temperature of 150-210 ℃ and the vacuum degree of 0.07-0.098 MPa, and extracting an isophthalonitrile product from the bottom of the product receiving kettle.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) the isophthalonitrile continuous rectification purification device provided by the invention can improve the content of the isophthalonitrile in the product and keep the purity of the isophthalonitrile stable to be more than or equal to 99.83 wt% and the molar yield to be more than or equal to 98.1% by combining the scraper evaporator with the rectification tower;
(2) according to the isophthalonitrile continuous rectification and purification device provided by the invention, the isophthalonitrile is continuously vaporized, rectified and purified in the scraper evaporator and the rectifying tower, so that the content of cyanobenzamide in the middle of a product can be reduced to be less than or equal to 0.11 wt% from 2.55 wt% before refining, the residue generation amount of a melting kettle in the downstream chlorothalonil production is greatly reduced, the content of hexachlorobenzene in the downstream chlorothalonil product is reduced to 10ppm, the product quality of chlorothalonil is improved, and the environmental pressure is relieved;
(3) the isophthalonitrile continuous rectification and purification device provided by the invention can realize continuous production through the scraper evaporator and the rectification tower, and has the advantages of stable product quality and low operation cost.
Drawings
FIG. 1 is a diagram of an apparatus for continuous rectification and purification of isophthalonitrile provided in example 1 of the present invention.
In the figure: 1-plunger type feeding metering pump; 2-melting the intermediate tank; 3-a scraper evaporator; 4-a first coke cutting kettle; 5-a second coke cutting kettle; 6-a continuous rectification column; 7-a tube array type secondary condenser; 8-a shell and tube product condenser; 9-a product receiving kettle; 10-plunger type material beating metering pump; 11-a slag discharge groove; 12-a first product trap; 13-a second product trap; 14-a first water-ring vacuum pump; 15-second water-ring vacuum pump.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
First, an embodiment
Example 1
This example provides an isophthalonitrile continuous distillation purification apparatus, as shown in fig. 1, comprising a raw material supply unit, a purification unit and a product receiving unit connected in sequence, wherein,
the raw material supply unit includes: the raw material supply unit includes: a plunger type feeding metering pump 1, a melting intermediate tank 2, a scraper evaporator 3, a first coke cutting kettle 4 and a second coke cutting kettle 5; wherein the plunger type feeding metering pump 1, the melting intermediate tank 2 and the scraper evaporator 3 are sequentially connected, a stirring device is arranged in the scraper evaporator, the scraper is in a limiting hinge scraper form, the bottom of the scraper evaporator 3 is respectively connected with the tops of the first coke cutting kettle 4 and the second coke cutting kettle 5, a first valve, namely a valve V3 and a valve V6, is arranged on a connecting pipeline, the tops of the first coke cutting kettle 4 and the second coke cutting kettle 5 are also connected with an outlet pipeline of the scraper evaporator 3, a second valve, namely a valve V1 and a valve V4, is arranged on the connecting pipeline, a discharge outlet is arranged at the top of the first coke cutting kettle 4 and the second coke cutting kettle 5, a third valve, namely a valve V2 and a valve V5, is arranged at the discharge outlet, the melting intermediate tank 2, the scraper evaporator 3, the first coke cutting kettle 4 and the second coke cutting kettle 5 are all made of stainless steel 304, the periphery of the plunger type feeding metering pump 1 is provided with a jacket for heat preservation, heat conducting oil is adopted in the jacket for heating, connecting pipelines among the plunger type feeding metering pump 1, the melting intermediate tank 2, the scraper evaporator 3, the first coke cutting kettle 4 and the second coke cutting kettle 5 are all jacket pipelines, and the materials of the jacket pipelines are all stainless steel 304;
the purification unit includes: a rectifying tower 6, a tube array type secondary condenser 7 and a slag discharge groove 11; the middle section of the rectifying tower 6 is connected with the top of a scraper evaporator 3 of a raw material supply unit, a tubular tower top condenser is arranged at the tower top, a side line extraction port is arranged on the tower top condenser, a tubular secondary condenser 7 is arranged at the tower top outlet of the rectifying tower 6, a tubular tower bottom reboiler is arranged at the tower bottom, packing is filled in the rectifying tower, a heat tracing pipe is arranged on the outer wall of the rectifying tower, a slag discharge groove 11 is arranged at the tower bottom outlet of the rectifying tower, a jacket is arranged around the slag discharge groove 11 for heat preservation, heat conduction oil is adopted in the jacket for heating, connecting pipelines among the scraper evaporator 3, the rectifying tower 6 and the tubular secondary condenser 7 are all jacket pipelines, and the jacket pipelines, a tower body of the rectifying tower 6, the tubular secondary condenser 7 and the slag discharge groove 11 are all made of stainless steel;
the product receiving unit includes: a tubular product condenser 8, a product receiving kettle 9, a plunger type material beating metering pump 10, a first product catcher 12, a second product catcher 13, a first water ring vacuum pump 14 and a second water ring vacuum pump 15, wherein the top of the product receiving kettle 9 is simultaneously connected with a side line outlet of a tubular tower top condenser of a rectifying tower 6 of a purifying unit and the bottom of a tubular secondary condenser 7, the plunger type material beating metering pump 10 is arranged at the bottom of the product receiving kettle 9, the tubular product condenser 8 is arranged at a top outlet, the top and the bottom of the tubular product condenser 8 are respectively connected with the top of the product receiving kettle 9, a baffle is arranged inside the top connection, the first product catcher 12 and the second product catcher 13 of a filter screen are arranged at a gas phase outlet, the first product catcher 12 is connected with the first water ring vacuum pump 14, the second product catcher 13 is connected with the second water-ring vacuum pump 15, the product receiving kettle 9 is provided with a jacket around for heat preservation, heat conducting oil is adopted for heating in the jacket, the first product catcher 12 and the second product catcher 13 are provided with a jacket around, circulating cooling water is introduced into the jacket, the tubular product condenser 8, the product receiving kettle 9, the first water-ring vacuum pump 14 and the second water-ring vacuum pump 15 are all made of stainless steel 304, and the first product catcher 12 and the second product catcher 13 are made of carbon steel.
Example 2
The embodiment provides an isophthalonitrile continuous rectification and purification device, which comprises a raw material supply unit, a purification unit and a product receiving unit which are connected in sequence, wherein,
the raw material supply unit includes: a plunger type feeding metering pump 1, a scraper evaporator 3, a first coke cutting kettle 4 and a second coke cutting kettle 5; wherein the plunger type feeding metering pump 1 and the scraper evaporator 3 are sequentially connected, a stirring device is arranged in the scraper evaporator, the scraper is in the form of a limiting hinge scraper, the bottom of the scraper evaporator 3 is respectively connected with the tops of the first coke cutting kettle 4 and the second coke cutting kettle 5, a first valve, namely a valve V3 and a valve V6, is arranged on a connecting pipeline, the tops of the first coke cutting kettle 4 and the second coke cutting kettle 5 are also connected with an outlet pipeline of the scraper evaporator 3, a second valve, namely a valve V1 and a valve V4, is arranged on the connecting pipeline, a discharge port is arranged at the top of the first coke cutting kettle 4 and the top of the second coke cutting kettle 5, a third valve, namely a valve V2 and a valve V5, the scraper evaporator 3, the first coke cutting kettle 4 and the second coke cutting kettle 5 are all made of stainless steel 304, a jacket is arranged around the periphery of the scraper evaporator and the jacket is heated by heat conducting oil, connecting pipelines among the plunger type feeding metering pump 1, the scraper evaporator 3, the first coke cutting kettle 4 and the second coke cutting kettle 5 are all jacket pipelines, and the jacket pipelines are all made of stainless steel 304;
the purification unit and the product receiving unit are identical in arrangement and connection to those of example 1, that is, the same as example 1 except for the melting intermediate tank not including the raw material supply unit of example 1 and the corresponding connection.
Comparative example 1
This comparative example provides an isophthalonitrile purification apparatus, and compared with example 1, the raw material supply unit provided by this comparative example was the same as that of example 1 except that the scraper evaporator in example 1 was replaced with a flash evaporator.
Comparative example 2
Compared with the embodiment 1, the comparison example provides an isophthalonitrile purification device, omits the rectifying tower in the embodiment 1, directly connects the top of the scraper evaporator with the top of the tubular secondary condenser, and the rest is the same as the embodiment 1.
Second, application
Application example 1
The application example provides a method for performing isophthalonitrile continuous rectification purification by using the device in the embodiment 1, and the method comprises the following steps:
(1) continuously introducing an m-phthalonitrile raw material from a batch distillation process receiving kettle into a melting intermediate tank 2 with the temperature of 150 ℃ through a plunger type feeding metering pump 1 for melting;
(2) vaporizing the isophthalonitrile raw material flowing out of the melting intermediate tank 2 in a scraper evaporator 3 with the temperature of 220 ℃ and the vacuum degree of 0.095MPa, intermittently and alternately flowing liquid-phase isophthalonitrile incompletely vaporized in the scraper evaporator 3 into a first coke cutting kettle 4 and a second coke cutting kettle 5 with the temperature of 150 ℃, and collecting for later use;
(3) introducing the vaporized isophthalonitrile in the scraper evaporator 3 into the middle section of a rectifying tower 6, rectifying and purifying to obtain purified isophthalonitrile, extracting liquid-phase phthalonitrile from a side line extraction port of a condenser at the top of the rectifying tower 6, introducing non-condensable gas at the top of the rectifying tower into a tubular secondary condenser 7 for secondary condensation, putting high-boiling-point substances at the bottom of the rectifying tower into a slag discharge groove 11, regularly discharging slag and barreling, wherein the vacuum degree of the rectifying tower 6 is 0.095MPa, the rectifying section temperature of the rectifying tower is 210 ℃, the stripping section temperature is 310 ℃, the temperature of the tubular overhead condenser is 210 ℃, the temperature of a reboiler at the bottom of the tubular tower is 310 ℃, the temperature of the tubular secondary condenser 7 is 210 ℃ and the temperature of the slag discharge groove 11 is 310 ℃;
(4) introducing liquid-phase isophthalonitrile extracted from a side extraction port of the overhead condenser and extracted from the bottom of the tubular secondary condenser 7 into a product receiving kettle 9 with the vacuum degree of 0.095MPa and the temperature of 150 ℃, extracting an isophthalonitrile product from the bottom of the product receiving kettle 9, and introducing the isophthalonitrile product into a chlorothalonil workshop through slicing by a slicer or through a plunger type knockout metering pump 10;
(5) introducing the m-phthalonitrile which is not completely condensed in the product receiving kettle 9 into a tubular product condenser 8 at the temperature of 120 ℃ for secondary condensation, returning the condensed liquid phase m-phthalonitrile in the tubular product condenser 8 into the product receiving kettle as a liquid phase product, and collecting the uncondensed tail gas in the tubular product condenser 8 into solid powder through a first product catcher 12 and a second product catcher 13 at the temperature of 90 ℃ under the vacuum degree of 0.095MPa, thereby obtaining a qualified product.
According to the application example, the device provided by the embodiment 1 is adopted to produce the isophthalonitrile, the purity of the obtained isophthalonitrile product is 99.85 wt%, the molar yield is 98.5%, and the isophthalonitrile produced by the application example is adopted to produce downstream chlorothalonil, so that the content of hexachlorobenzene in the chlorothalonil product is reduced to 10ppm, and the product quality of the chlorothalonil is improved.
Application example 2
The present application example provides a method for performing continuous rectification and purification of isophthalonitrile by using the apparatus described in example 2, which is different from application example 1 in that the melting operation of isophthalonitrile is not performed, and an isophthalonitrile raw material is directly introduced into a scraper evaporator, and the method specifically includes the following steps:
(1) continuously introducing an isophthalonitrile raw material from a receiving kettle of the batch distillation process into a scraper evaporator 3 through a plunger type feeding metering pump 1;
(2) vaporizing the isophthalonitrile raw material in a scraper evaporator 3 with the temperature of 220 ℃ and the vacuum degree of 0.095MPa, intermittently and alternately flowing incompletely vaporized liquid-phase isophthalonitrile in the scraper evaporator 3 into a first coke cutting kettle 4 and a second coke cutting kettle 5 with the temperature of 150 ℃, and collecting for later use;
the operation steps and process parameters in step (3), step (4) and step (5) are the same as those in application example 1.
Application comparative example 1
Comparative example of the present application provides a method for purifying isophthalonitrile using the apparatus described in comparative example 1, differing from application example 1 only in that a blade evaporator was replaced with a flash evaporator, and the remaining operational steps and process parameters were the same as in application example 1, wherein the specific steps for the flash evaporator in step (2) were as follows:
(2) vaporizing the isophthalonitrile raw material flowing out of the melting intermediate tank 2 in a flash evaporator with the temperature of 220 ℃ and the vacuum degree of 0.095MPa, intermittently and alternately flowing liquid-phase isophthalonitrile incompletely vaporized in the flash evaporator into a first coke cutting kettle 4 and a second coke cutting kettle 5 with the temperature of 150 ℃, and collecting for later use; the switching operation steps of the first coke cutting kettle 4 and the second coke cutting kettle 5 are the same as those of application example 1.
Comparative application example 2
Compared with the application example 1, the method for purifying the isophthalonitrile by using the device in the comparative example 2 omits the rectification process, directly introduces the isophthalonitrile vaporized in the scraper evaporator into the condenser for condensation and recovery, and specifically replaces the steps (3) to (4) in the application example 1 with the following steps:
(3) introducing the vaporized isophthalonitrile in the scraper evaporator 3 into a secondary condenser 7 for secondary condensation, wherein the temperature of the secondary condenser 7 is 210 ℃;
(4) introducing the liquid-phase isophthalonitrile extracted from the bottom of the secondary condenser 7 into a product receiving kettle 9 with the vacuum degree of 0.095MPa and the temperature of 150 ℃, extracting an isophthalonitrile product from the bottom of the product receiving kettle 9, and introducing the isophthalonitrile product into a chlorothalonil workshop through slicing by a slicer or through a plunger type knockout metering pump 10;
the remaining steps and operating parameters were the same as in application example 1.
The raw material of isophthalonitrile was treated in application examples 1 to 2 and application comparative examples 1 to 2, and the resulting isophthalonitrile product and the recovery rate of isophthalonitrile were analyzed, and the analysis results are shown in table 1.
TABLE 1
From table 1, the following points can be seen:
(1) it can be seen from the comprehensive application examples 1 and 2 that the isophthalonitrile continuous rectification purification device provided by the invention is applied to isophthalonitrile purification, the purity of the prepared isophthalonitrile product is more than or equal to 99.83 wt%, the content of the m-cyanobenzamide is less than or equal to 0.11 wt%, and the content of the terephthalonitrile is less than or equal to 0.04 wt%, so that the content of hexachlorobenzene in downstream chlorothalonil is as low as 10ppm, and meanwhile, the molar yield of the isophthalonitrile is more than or equal to 98.1%, which indicates that the isophthalonitrile continuous rectification purification device provided by the invention is used for rectifying and purifying isophthalonitrile, not only can stable and continuous production be realized, but also higher isophthalonitrile product purity and recovery rate can be obtained;
(2) by combining application example 1 and application comparative example 1, it can be seen that, by arranging the scraper evaporator in front of the rectifying tower in application example 1, compared with the application comparative example 1 adopting the flash evaporator, the purity of the isophthalonitrile product obtained in application example 1 is 99.85 wt%, the molar recovery rate is 98.5%, and the purity of the isophthalonitrile product obtained in application comparative example 1 is only 99.35 wt%, and the molar yield is only 97.1%, so that the isophthalonitrile has a higher heat exchange coefficient by adopting the scraper evaporator to evaporate isophthalonitrile, so that the isophthalonitrile has a shorter retention time, the coking and deterioration of the thermosensitive isophthalonitrile is reduced, and the purity and yield of the final isophthalonitrile product are improved;
(3) combining application example 1 and application comparative example 2, it can be seen that application example 1 can be better separated from impurities in the raw material by adding a rectification column after a scraper evaporator, compared to application comparative example 2 using only a scraper evaporator, the isophthalonitrile product obtained in application example 1 has a purity of 99.85 wt%, wherein the content of m-cyanobenzamide is only 0.09 wt%, the content of terephthalonitrile is only 0.04 wt%, and the molar recovery rate of the isophthalonitrile product is 98.5%, while application comparative example 2 has a purity of 99.51 wt%, wherein the content of m-cyanobenzamide is up to 0.32 wt%, the content of terephthalonitrile is up to 0.15 wt%, and the molar yield of the isophthalonitrile product is only 98.1%, by adding a rectification column after a scraper evaporator, the isophthalonitrile is rectified and purified after evaporation, the content of the intermediate cyanobenzamide in the product is reduced, and the isophthalonitrile product with higher purity is obtained.
In conclusion, the isophthalonitrile product prepared by the isophthalonitrile continuous rectification and purification device provided by the invention has the purity of more than or equal to 99.83 wt%, wherein the content of the m-cyanobenzamide is less than or equal to 0.11 wt%, so that the hexachlorobenzene content in downstream chlorothalonil is only 10ppm, and the molar yield of the m-phthalonitrile is more than or equal to 98.1%, thereby effectively reducing the content of the m-cyanobenzamide in the product.
The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. The device for continuously rectifying and purifying the isophthalonitrile is characterized by comprising a raw material supply unit and a purification unit which are sequentially connected;
the raw material supply unit comprises a scraper evaporator;
the purification unit comprises a rectifying tower;
the top of the scraper evaporator is connected with the middle section of the rectifying tower through a pipeline.
2. The apparatus according to claim 1, wherein a stirring device is provided inside a scraper evaporator in the raw material supply unit;
preferably, the scraper of the scraper evaporator is in the form of a limiting hinge scraper, a flexible scraper, a hinge scraper, an elastic scraper, a scraper-type scraper, a movable scraper or a fixed scraper;
preferably, the scraper evaporator is jacketed;
preferably, heat conducting oil is adopted to heat the inside of a jacket of the scraper evaporator;
preferably, the material of the scraper evaporator is stainless steel, Monel 400 or Hastelloy, and is preferably stainless steel 304.
3. The apparatus according to claim 1 or 2, wherein the raw material supply unit further comprises a feed metering pump and a melting intermediate tank which are connected in series by a pipe;
preferably, the feed metering pump is a plunger metering pump;
preferably, the melting intermediate tank and the scraper evaporator are connected in sequence;
preferably, the melting intermediate tank is provided with a jacket;
preferably, the jacket of the melting intermediate tank is heated by adopting heat conducting oil;
preferably, the material of the melting intermediate tank is stainless steel, Monel 400 or Hastelloy, and the material is preferably stainless steel 304.
4. The apparatus according to any one of claims 1 to 3, wherein the raw material supply unit further comprises a coke cutting kettle connected to the scraper evaporator;
preferably, the top of the coke cutting kettle is connected with the bottom of the scraper evaporator;
preferably, the top of the coke cutting kettle is connected with a top outlet pipeline of the scraper evaporator;
preferably, a discharge hole is formed in the top of the coke cutting kettle;
preferably, the number of the coke cutting kettles is at least two;
preferably, the coke cutting kettle is provided with a jacket;
preferably, heat conducting oil is adopted to heat the jacket of the coke cutting kettle;
preferably, the material of the coke cutting kettle is stainless steel, Monel 400 or Hastelloy, and stainless steel 304 is preferred.
5. The device according to any one of claims 1 to 4, wherein an overhead condenser is arranged at the top of the rectifying tower of the purifying unit;
preferably, the overhead condenser is a shell and tube condenser;
preferably, the overhead condenser is provided with a side draw outlet;
preferably, the tower bottom of the rectifying tower is provided with a tower bottom reboiler;
preferably, the bottom reboiler is a shell and tube reboiler;
preferably, the rectifying tower is internally provided with packing or trays;
preferably, the outer wall of the rectifying tower is provided with a heat tracing pipe;
preferably, the material of the body of the rectifying tower is stainless steel, Monel 400 or Hastelloy, and stainless steel 304 is preferred.
6. The device according to any one of claims 1 to 5, wherein a secondary condenser is arranged at the top outlet of the rectifying tower of the purifying unit;
preferably, the secondary condenser is a shell and tube heat exchanger;
preferably, a slag discharging groove is arranged at the bottom outlet of the rectifying tower;
preferably, the slag discharging groove is provided with a jacket;
preferably, heat conducting oil is adopted to heat the inside of a jacket of the slag discharging groove;
preferably, the material of the secondary condenser is stainless steel, Monel 400 or Hastelloy, preferably stainless steel 304;
preferably, the material of the slag discharge groove is stainless steel, Monel 400 or Hastelloy, and stainless steel 304 is preferred.
7. The apparatus of any one of claims 1 to 6, further comprising a product receiving unit after the purification unit;
preferably, the product receiving unit comprises a product receiving kettle connected with the rectifying tower;
preferably, the top of the product receiving kettle is connected with a side line outlet of an overhead condenser;
preferably, the top of the product receiving kettle is connected with the bottom of the secondary condenser;
preferably, the product receiving vessel is jacketed;
preferably, the jacket of the product receiving kettle is heated by adopting heat conducting oil;
preferably, the material of the product receiving kettle is stainless steel, Monel 400 or Hastelloy, and stainless steel 304 is preferred.
8. The device according to any one of claims 1 to 7, wherein a slicer or a knockout metering pump is arranged at the bottom of the product receiving kettle in the product receiving unit;
preferably, the ramming material metering pump is a plunger type metering pump;
preferably, a product condenser is arranged at the top outlet of the product receiving kettle;
preferably, the top of the product condenser, and/or the bottom of the product condenser is connected to the top of the product receiving vessel;
preferably, the material of the product condenser is stainless steel, Monel 400 or Hastelloy, and preferably stainless steel 304.
9. The apparatus according to any one of claims 1 to 8, wherein a product catcher is provided at the top of the product receiving tank in the product receiving unit;
preferably, a baffle is disposed inside the product trap;
preferably, a gas phase outlet of the product catcher is provided with a filter screen;
preferably, the product traps are provided in at least two;
preferably, a jacket is arranged around the product catcher;
preferably, circulating cooling water, cold air, low-temperature water or frozen brine is introduced into a jacket of the product catcher;
preferably, the product catcher is made of carbon steel or stainless steel;
preferably, the product trap is connected to a vacuum pump;
preferably, the vacuum pump is a water-ring vacuum pump, a piston vacuum pump or a roots vacuum pump, preferably a water-ring vacuum pump;
preferably, the material of the vacuum pump is carbon steel or stainless steel.
10. The device according to any one of claims 1 to 9, wherein connecting pipelines among the feeding metering pump, the melting intermediate tank, the scraper evaporator, the coke cutting kettle, the rectifying tower, the secondary condenser and the product receiving kettle are all jacketed pipelines;
preferably, the material of the jacket pipeline is stainless steel, Monel 400 or Hastelloy, and the jacket pipeline is preferably stainless steel 304.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111440092A (en) * | 2020-03-30 | 2020-07-24 | 江苏维尤纳特精细化工有限公司 | Safe and automatic m-phthalonitrile refining process |
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